Thermostatic device



Sept. 20, 1949. J. o. YElDA THERMOSTATIC DEVICE Filed Nov. 3, 1944 l 4w]w u 4 0 4 T A J w M nmH fl ll! 2 s A M 2 m a Kw a m.

Patented Sept. 20, 1949 UNITED- STATES PATENT OFFICE THERMQSTATIG DEVIGEJohn Yei lal, Herculaneum, Mo., assignor, by mesne assignments, toMissouri Automatic Control Corporation, a corporation of Missouri Appliation November 3, 1944, erial No- 561,775.

2 Claims. 1

This invention relates to a thermostatic device, and more particularlyto one that is responsive only to variable temperature conditions withinitself.

An object of the invention is to provide a simple thermostat of thiskind, which is structurally strong and which functions r pidly.

A iurther object is to provide a thermostatic device in the form of achannel-shaped member designed so that flame applied to the flanges willcause av portion of them to expand more than the corresponding portionof the bottom wall of the channel, with resultant distortion of one endof the member. More particularly, it is an object to provide such achannel member in combination with a heat absorbing member adjacent thebottom wall to aid in the heat differential between the flanges and thebottom wall.

An especial object is to provide such a channel-shaped member in aU-shape, to attain compactness and maximum movement of the actuating endthereof.

In the drawings:

Fig. 1 is a side elevation of the device;

Fig. 2 is an edge elevation of Fig. 1; and

Fig. 3 is a vertical section taken on the line 3-3 of Fig. 1.

The device includes a base member In adapted to be secured to a propersupport by screws passing through holes II. The base I!) may be attachedto the wall of a furnace adjacent a pilot burner shown at 12.

The base has a projection l3 preferably rounded, as shown at 14, at itsupper end.

A channeled strip of uniform composition, generally indicated at l6, hasa back leg ll attached at one edge of the projection l3 on the base Ill.The channel strip [6 is U-shaped having a bight portion l8 curved overthe curved portion at the top of the projection l3. Preferably theprojection 13 is no Wider than the channel section. The channel also hasan operating leg I 9 extending down the other edge of the projection l3closely adjacent thereto but spaced therefrom. At its free end, the armI 9 carries a double throw switch blade 20 having a switch arm 2|supporting two contacts 22 cooperable with either contacts 23 on thebase ID, or with contacts 24 supported on a bracket 25 mounted on andinsulated from the base In. This switch is typical of devices to beoperated by the element. Each of the contacts 22 and each of thecontacts 23 is insulated one from the other. The various contacts areadapted to be connected by leads 26 with suitable circuits,

2 such as solenoid valve circuits, or. the like, con, trolling the flowof fuel to the burner.

The. channel section should be rather narrow, with flanges that are deeprelative to its width. For example, a channel with a A" space betweenflanges deep has proved successful. The depth of the flanges should besuch that a flame impingin upon their outer portions will not impingewith equal heat upon the bottom wall.

Operation This control is adapted to be used. in such places as afurnace, where it is subject to variat-v tion in ambient temperatures.Despite normal changes in ambient temperature, that afiect all parts ofthe element, it will also respond to the presence or absence of a flameF at the pilot burner l2.

When the element is not subjected to the pilot flame, it will assume theposition shown in Fig. 1, wherein the contacts '22 close with thecontacts 24. This may control a circuit to an igniter for the pilotburner. When the flame F impinges against the channel element. a largequantity of heat is introduced into the flanges. The narrow and deepchannel section will take most of the heat in the flanges, which therebyexpand to a greater degree than the bottom wall expands. As a result,the channel element warps, causing the contact member 20 to separate thecontacts 22 from the contacts 24, and to move to bridge the contacts 23.When the device is used as a pilot flame detector, this operation willthen permit a fuel valve circuit to close.

The warping is accentuated by having the bottom wall of the channellocated so as to give off heat constantly. While the flanges are bathedin the flame, the bottom wall is more or less spaced from the flame.Also the back side is to a large extent, and preferably adjacent theflame, disposed against the relatively cooler projection 13, which canabsorb heat therefrom, and, in any case, is exposed to air at lowertemperature than the temperature of the flame. Hence the outer part ofthe flanges will always be hotter than the inner parts, duringimpingement of flame.

Curving the element to the U-shape increases the warping, as itincreases the proportion of the element that is in direct contact withthe projection l3. The spacing of the free arm l9 from the projection I3is preferably the minimum, being only enough to permit proper switchoperation.

Ambient heat afiects all parts of the device cause the switch tofunction. It will be seen that the device is of a rigid construction,free of pivots and like parts subject to wear and displacement. 7

What is claimed is: a 1. In a thermostatic device, tion extending fromthe base and providing p- .10 the proper action of the expanding partsto;

channel-shaped member of uniform composition secured to one side of theprojection near the base and extending along said side in contacttherewith, said member extending around said connecting'side of theprojection in contact with a portion thereof and extending down theother side of the projection in spaced relation thereto, saidchannel-shaped member having the flanges thereof extending outwardlyfrom the Projection, actuated means associated with the free end of 5said member, the free end of said member being adapted to assume andremain in one position a base, a projecposite sides and a connectingside, a unitary;

heat-responsive channel-shaped member secured to one side of theprojecting portion remote from the connecting side, extending along tothe flanges of said member.

said sidein contact therewith, extending around 1 said connecting sideof the projecting portion and extendingdown the other side of theprojecting portion, said member being substantially uniform incomposition, actuated means associated with the free end of said member,said member being adapted to be impinged upon by a flame applied to theflanges thereof.

2. A thermostatic device comprising a base, a projection extending fromthe base and including opposite sides and a connecting side remote fromthe base, a unitary heat-responsive upon impingement of the flame on theflanges thereof and being adapted to assume and remain in anotherposition in the absence of heat greater than ambient temperature, theprojection being adapted to absorb heat from the bottom wall of saidmember to accentuate the difference in temperature between the flangesand the bottom wall of said member when a flame is applied 7 JOHN O.YEIDA.

REFERENCES" CITED The following references are of record in the file ofthis patent;

UNITED STATES PATENTS '7 Number Name 7 Date 2 1,233,223 Hachmann" July10, 1917 2,064,909. Hahn Dec., 22, 193 2,080,385 Congdon f 'May 11, 19372,288,746 7 Samuels July 7,

